I. Definitions
As used herein, the phrase “group III-V” refers to a compound semiconductor that includes a group V element and at least one group III element. Moreover, the phrase “III-Nitride” or “III-N” refers to a compound semiconductor that includes nitrogen (N) and at least one group III element, including aluminum (Al), gallium (Ga), indium (In), and boron (B), and including but not limited to any of its alloys, such as aluminum gallium nitride (AlxGa(1-x)N), indium gallium nitride (InyGa(1-y)N), aluminum indium gallium nitride (AlxInyGa(1-x-y)N), gallium arsenide phosphide nitride (GaAsaPbN(1-a-b)), and aluminum indium gallium arsenide phosphide nitride (AlxInyGa(1-x-y)AsaPbN(1-a-b)), for example. III-Nitride also refers generally to any polarity including but not limited to Ga-polar, N-polar, semi-polar or non-polar crystal orientations. A III-Nitride material may also include either the Wurtzitic, Zincblende, or mixed polytypes, and may include single-crystal, monocrystalline, polycrystalline, or amorphous structures.
Also as used herein, the phrase “group IV” refers to a semiconductor that includes at least one group IV element, including silicon (Si), germanium (Ge), and carbon (C), and also includes compound semiconductors such as SiGe and SiC, for example. Group IV may also refer to a semiconductor material which consists of layers of group IV elements or doping of group IV elements to produce strained silicon or other strained group IV material. In addition, group IV based composite substrates may include semiconductor on insulstor (SOI), separation by implantation of oxygen (SIMOX) process substrates, and silicon on sapphire (SOS), for example. Moreover, a group IV device may include devices formed using standard CMOS processing, but may also include NMOS and PMOS device processing.
The group III-V device can include any suitable semiconductor material that forms a field-effect transistor (FET) such as an insulated-gate FET (IGFET), or a high electron mobility transistor (HEMT), for example. Suitable semiconductor materials include group IV semiconductor materials such as Si, strained silicon, SiGe, SiC, and group III-V materials including III-As, III-Nitride or any of their alloys.
II. Background Art
Group III-V transistors, such as III-Nitride field-effect transistors (III-Nitride FETs) and III-Nitride high mobility electron transistors (III-Nitride HEMTs), are often utilized in high power switching applications due to their performance advantages. For example, III-Nitride FETs and III-Nitride HEMTs have a well deserved reputation for low on-state resistance with the ability to sustain high operating voltages.
However, and perhaps because of their tolerance for high voltage operation, high voltage (HV) group III-V transistors are sometimes implemented in extreme operating environments in which very high voltages can be produced. As a result, even nominally HV rated III-Nitride FETs and HV rated III-Nitride HEMTs may be susceptible to catastrophic failure in practice.